It is known that unmanned aerial vehicles, or UAVs, may be equipped with a pair of optical elements that guide light to image sensors, and that images of an object captured by the image sensors may be used to determine parallax disparity of the object. In such UAVs, the optical elements are mounted on the UAVs and face forward when the UAVs operate leveled with respect to ground. When the UAVs tilt during flight, the optical elements also tilt with the UAVs. For example, when the UAVs are moving forward, the UAVs tilt downwards, and the optical elements, and their fields of view, also tilt downwards. Such tilting may cause the fields of view of the optical elements to include little or no view of the path in front of the UAV.